1. Field of the Invention
The present invention relates to a portable dot printing device for printing dots on printing mediums, such as printing sheets.
2. Description of the Related Art
Japanese Patent Application (Kokai) No. 48-17630 describes a manual dot printing device capable of printing at a desired position on a printing medium when manually scanned across the printing medium. The manual printing device is capable of printing on various printing mediums regardless of the size or the thickness of the printing medium, thereby overcoming a limitation of other printing devices capable of printing on only certain sized recording mediums by limitations of their casing size or their sheet-transport mechanisms.
To print characters on a printing medium with greater precision and at a higher density, the relative movement of the print head across the printing medium has to be precisely detected by an encoder of the device. Generally, the relative movement of a print head across the printing medium is detected by a pulse waveform. The print head can be formed with nozzles aligned in rows. When the minimum unit of movement detectable by the encoder, or one pulse, is not equal to the distance between adjacent nozzle rows formed in the print head, even if the movement amount of the print head is detected precisely, the rows of the nozzles cannot precisely print based on the print head movement.